1. Field of the Invention
The present invention relates to a printing method and printer. More particularly, the present invention relates to a printing method and printer in which a printing head can be readily inspected, and failure in printing can be detected with certainty.
2. Description Related to the Prior Art
Printers of various types are known, including an ink jet printer having an ink jet printing head, and a thermal printer having a thermal head. It is likely in the ink jet printer that failure occurs in operation of nozzles or recording elements of the printing head because of certain reasons. For example, choking of ink may occur in the nozzles. An abnormal situation of a drop of the ejected amount occurs. Furthermore, the nozzles come not to eject ink. Streaks occur in imaged printed by the printing head because of unevenness in color or density.
To inspect the printing head, printed images are observed. If streaks occur due to unevenness in color or density, then a cleaning mode is set to clean the printing head to eliminate choking of the ink or remove abnormality in a direction of ejecting the ink. In the cleaning, the ink is ejected through the nozzles at a high flow rate. Also, the ink is sucked externally from the nozzles. Furthermore, the nozzles are wiped. If the failure is eliminated according to manual operation, it is likely that discovery of choking of the ink is too late, to print an image with very low quality. Unlike a printer used personally at home by a user, a commercial use of the printer at a shop or by a dealer requires high quality in printing. If failure in operation of the nozzles is discovered too late, reliability in printing at the shop to customers is seriously lowered.
In view of the foregoing problems, an object of the present invention is to provide aprinting method and printer in which a printing head can be readily inspected, and failure in printing can be detected with certainty.
In order to achieve the above and other objects and advantages of this invention, a printer has a printing head, including plural recording elements arranged in a main scan direction. A moving mechanism moves one of the printing head and recording material relative to a remainder thereof in a sub scan direction. A controller drives the printing head and the moving mechanism to print at least one image and a head check pattern to the recording material, the head check pattern being printed outside a region of the image, and adapted to check whether the recording elements print at intended printing density.
Furthermore, a frame memory is connected with the controller, for storing information of the image. A pattern memory is connected with the controller, for storing information of the head check pattern.
The at least one image is plural images, and the head check pattern is printed to the recording material in a position between the plural images, in a position defined upstream therefrom, or in a position defined downstream therefrom.
Furthermore, a pattern reader reads the head check pattern. The controller designates failing recording elements among the plural recording elements by extracting pixels with low printing density within the head check pattern being read.
The controller causes the printing head to print cutting indicia to the recording material in respectively positions between the plural images, the cutting indicia being adapted to cut the recording material.
The controller, before printing the head check pattern, causes the printing head to print a trial printed pattern to the recording material.
The head check pattern and the trial printed pattern are combined to constitute at least one of the plural cutting indicia.
The printing head is an ink jet printing head, the plural recording elements are constituted by plural nozzles for ejecting an ink droplet to the recording material. The trial printed pattern is printed for cleaning the nozzles.
The printing head prints the head check pattern before printing the image. The controller, after printing the image, further causes at least failing nozzles among the plural nozzles to eject an ink droplet, to print a second trial printed pattern to the recording material.
The controller, after printing the second trial printed pattern, causes the printing head to print a second head check pattern to the recording material, the second head check pattern being adapted to check whether the nozzles print at intended printing density. The second head check pattern and the second trial printed pattern are combined with one another to constitute the cutting indicia.
The printing head prints the head check pattern in association with each of the plural images, or prints the head check pattern in a position between plural series of the images, or prints the head check pattern upon lapse of predetermined time, or prints the head check pattern when a roll of the recording material is replaced with a roll of new recording material.
The plural series are associated with respectively one request for printing, or each of the plural series includes a predetermined number of images.
The recording material is continuous recording sheet or a recording sheet strip. The controller further causes the printing head to print a sorting indicia to the recording material in a position between plural series of the images, the sorting indicia being discernible from the cutting indicia and adapted to designating the series of the images.
The sorting indicia is different from the cutting indicia in at least one of a width, length, position, color and shape.
The cutting indicia are constituted by respectively a combination of the head check pattern and a first type of the trial printed pattern, and the sorting indicia is constituted by respectively a combination of the head check pattern and a second type of the trial printed pattern, the second type being discernible from the first type.
The failure designating step includes generating an alarm signal for recovery of the failing recording elements.
Furthermore, after the failure designating step, ink is sucked from failing nozzles among the plural nozzles for recovery, or the failing nozzles are wiped for recovery.
In a preferred embodiment, the moving mechanism comprises a head carriage for moving the printing head in the sub scan direction for image printing in a belt shape. Furthermore, a second moving mechanism moves one of the head carriage and the recording material relative to a remainder thereof in the main scan direction, to print the image.